This is Lana from Shopify. I see you have a question regarding your Shipping Policy so I wanted to help you out.
To start I just wanted to highlight the difference between your Shipping Policy and Shipping Rates:
Going back to setting up your rates, once you open Settings > Shipping and Delivery, you will need to click on Manage rates where you will see that you can set up the Shipping zones:
In the above example you can see how the zones and rates are split up for domestic and international shipping.
In terms of what you should be charging, that is entirely up to you. Shipping rates are there for you to be able to cover that costs of shipping products out to your customers, so it has to be affordable for you. You can check what rates would be most suitable to set for your own store by looking into this with your local post office and seeing what you would need to cover there. The shipping rates can be edited at any time so you will be able to go back and change them if you ever feel that they are not appropriate.
Please check out our help doc on Shipping and Delivery to learn more, but also feel free to ask me any questions here.